Modern oil and gas wells are expensive and complicated. A large financial and technical investment is made in constructing a wellbore that may extend for miles below a geological surface. The subterranean formation through which the wellbore passes may have multiple producing zones or segments that are separated by hundreds or thousands of feet. Another very large financial and technical investment is made to install completion hardware and/or screens in the wellbore to prevent sand and particle penetration into the wellbore, thereby facilitating long-term production of oil and gas fluids. Once installed, it is very expensive and time consuming to remove such hardware. Thus, methods and techniques to accomplish objectives in a wellbore without the need to remove completion hardware are very desirable.
It has been observed that the fluid and solid materials generated by a given segment of an oil and gas producing formation changes over time during the twenty or thirty year life of a producing well. After expensive and complex completion hardware is installed in the well, it usually is cost prohibitive to remove such hardware to evaluate the production characteristics of the well in particular zones or segments of the well. For example, a particular producing zone after a number of years may begin producing excess amounts of water. Large volume water production is very costly to treat for disposal, and it displaces the volume of oil or gas that otherwise could be produced up the wellbore. Late in the life of many wells, the volume of water produced usually is much greater than the amount of oil produced. Currently, it is very difficult or impossible to determine which zone of the well is producing desirable oil or gas, and which zone is producing mostly undesirable water, especially if sand-control hardware is present in the completion design. Access to the pay-zones is limited due to many design constraints. The fluids from all of the zones typically are produced upwards into a common wellbore that extends to the geological surface.
It would be highly desirable if there was an apparatus, method or system for determining the flow characteristics downhole in one or more segments of a well. Such flow characteristics as the volume of water produced and the flow rate in a given segment of a well could be very useful in managing production of oil and gas from a well. Furthermore, once that information is known, it would be desirable to provide a method for adjusting the flow characteristics or quantity of a particular zone or segment of a well to increase the overall hydrocarbon production from the well.